Howlite was discovered in 1868 by a Nova Scotia chemist, geologist and mineralogist named Henry How. It is a calcium borosilicate hydroxide. It is usually white in color with veins of other minerals running through the nodules. They are easily distinguished by its inferior hardness – turquoise Moh’s hardness being 5-6 and Howlite – Moh’s hardness being 3.5.
Howlite develops in evaporate deposits and usually occurs with ulexite and colemanite as nodules in clay. Howlite has a white; subvitreous, glimmering, dull; streak white color and luster. A species very similar to Howlite is datolite which is harder than howlite and will not dissolve in hydrochloric acid. Howlite is easily fusible.
Howlite occurs with other boron minerals, such as kernite and borax, and is found in quantity in the Karamer district of Death Valley and San Bernardino County, California where you can find nodules sometimes several hundred pounds in weight, especially with colemanite at Lang, Los Angeles Co., and with ulexite near Daggett, San Bernardino Co.